Cable television systems allow subscribers access to dozens or even hundreds of channels of television programming. This wide variety of programming accounts for the great popularity of cable television. Additionally, the current trend is for cable television systems to provide additional services such as pay-per-view programming, video-on-demand programming, internet access and, eventually, telephony.
In advanced cable television systems, each subscriber is typically provided with a set-top terminal. The set-top terminal is a box of electronic equipment that is used to connect the subscriber's television, or other electronic equipment, to the cable television system. The set-top terminal processes the signal received from the cable television system to provide the services of the cable system to subscribers.
FIG. 1 illustrates a typical cable television system. The cable television signal, and any other services offered over the cable system, originate at the headend facility (101). The headend (101) may be the central operating facility of the cable system operator, or may be one of several regional headend facilities.
The cable television signal is distributed from the headend (101) to hubs (102). Typically, the communication between the headend (101) and the hubs (102) is accomplished by optical signaling over a fiber optic cable network (108). The hubs (102), in turn, distribute the cable television signal to a number of nodes (103). As with the headend-hub communication, the link between the hubs (102) and nodes (103) is typically a fiber optic cable network (109).
At each node (103), the optical signal from the hubs (102) is converted into a radio frequency (RF) signal for distribution on a co-axial cable network (104 to 106) to individual subscribers. A cable television system like the one described here, that includes both optical signaling over fiber optical cable and RF signaling over co-axial cable, is called a Hybrid Fiber Co-axial (HFC) network.
The co-axial cable network from the nodes (103) is divided into trunk lines (104), which branch into feeder lines (105), which branch into tap lines (106), resulting in the tree structure illustrated in FIG. 1. The tap lines (106) are connected to the set-top terminals (107) of individual subscribers to the cable system.
To support advanced features of the cable television system, it is necessary for the set-top terminal (107) to be able to, not just receive the cable television signal from the headend (101), but also communicate back “upstream” and send data or messages to the headend (101). In order to accomplish this, a return signal path may be provided within the system illustrated in FIG. 1.
For example, the set-top terminal (107) can use the tap line (106) to send a message upstream over the feeder (105) and trunk (104) lines to the node (103). To eliminate the “collision” of data coming upstream from the terminal (107) (e.g., poll responses) with the downstream signal from the headend (101), there will be a designated frequency at which a set-top terminal (107) must communicate upstream to the node (103). This frequency may be different for different nodes (103). Once the upstream signal from the set-top terminal (107) reaches the node (103), it is demodulated by a return path demodulator (RPD) (110).
The terminals and signal distribution devices in the headend (101), hubs (102) and nodes (103) are all controlled by a system controller (112). The controller (112) may be located at the central headend facility (not shown) and may control several regional headends (101). The controller (112) is connected to the regional headends (101), hubs (102) and nodes (103) by a separate data communication network (111), typically an ethernet. The return path demodulator (110) of the node (103) uses the ethernet (111) to transmit any messages received from the set-top terminal (107) via the return path demodulator (110) to the controller (112). The controller (112) can then initiate any response necessary to the set-top terminal communication.
Alternatively, each of the set-top terminals (107) may be connected to a telephone line and may communicate with the controller (112) by placing a call on that phone line to the controller (112). The controller (112) will have a bank of modems for receiving telephone calls from set-top terminals (107). This system avoids the need to provide a two-way data path within the cable television system itself, but also requires the expense of connecting each set-top terminal to a phone line.
There are a number of problems in operating the cable television systems described above. One prominent problem area arises when new set-top terminals are added to the system. When a new terminal is added, it must be properly configured to work within the system of the cable system operator. Each cable system is unique and may not precisely follow the hierarchy described above.
When new subscribers are added, an electronic billing system usually receives data about the new subscriber via manual entry and then determines and assigns attributes to each terminal to allow the terminal to operate within the system. Such attributes may include a credit limit for video services ordered from the terminal, the channel map for the television channels available to the terminal, the time zone in which the terminal resides, etc.
Some or all of these attributes may depend on where the terminal is located within the system, for example, the local time zone of the terminal. These location-dependent attributes are important. For example, if the terminal is accessing an electronic programming guide, the appropriate guide may be dictated, in part, by the time zone in which the terminal is located.
Additionally, some particular channels, perhaps those of local interest, may be available in some parts of the cable system but not others. Thus, some terminals in the system may need a different channel map or a different electronic programming guide than others. In another example, as noted above, the frequency at which a set-top terminal (107) communicates upstream may vary depending on the node (103) to which the terminal (107) is connected.
Thus, in order for a new terminal (107) to be successfully added to the system, its location must be identified so that it can be configured properly. However, the electronic billing system usually has limited information on where the new terminal is being physically added to the system and that information is often inaccurate, being subject to human error during input. Thus, in order for a new terminal to be properly configured based on its location within the system, a technician is usually required to install the set-top terminal, note its location and configure the terminal appropriately. This requires an expense in time and trained personnel to properly add new subscribers to the system. This is especially problematic for the retail distribution model where subscribers purchase the terminal at a retail outlet and install it themselves.
Consequently, there is a need in the art for a system and method allowing the controller (112) to automatically determine the physical location of a set-top terminal within the system so as to more easily configure and initialize that terminal based on its location within the system.